ISSN:
1432-2013
Keywords:
Thermal conductivity
;
Microcirculation
;
Flowmeters
;
Blood flow velocity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary An isothermal flowmeter with improved frequency response for measuring tissue blood flow was developed using thermistors. Direct heating of the thermistors allows a simple construction of small (0.5 mm outer diameter) capillary probes which do not require any additional heating coil. The changes of a feedback current necessary to keep the thermistor at a constant increment above tissue temperature indicate tissue blood flow; a second thermistor compensates variations of tissue temperature. The dynamic performance of the device shows a low-pass characteristic with a cut-off frequency higher than 5 Hz. For low flow rates the output signal was found to be proportional to the flow; for higher flow rates a linearization was necessary. Since tissue temperature can be recorded continuously, intermittent quantitative in-vivo calibration seems possible by evaluation of “heater off” curves in the perfused and non-perfused tissue. As the flowmeter is insensitive to tissue temperature, it can be used for long-term recordings.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00583661
Permalink
